Don't use 'new Function' for lazily initialized getter.

sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart	(revision 15244)
+++ sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart	(working copy)
@@ -322,14 +322,21 @@
 
   String get lazyInitializerFunction {
     String isolate = namer.CURRENT_ISOLATE;
+    return """
+function(prototype, staticName, fieldName, getterName, lazyValue) {
+  var getter = new Function("{ return $isolate." + fieldName + ";}");
+$lazyInitializerLogic
+}""";
+  }
+
+  String get lazyInitializerLogic {
+    String isolate = namer.CURRENT_ISOLATE;
     JavaScriptBackend backend = compiler.backend;
     String cyclicThrow = namer.isolateAccess(backend.cyclicThrowHelper);
     return """
-function(prototype, staticName, fieldName, getterName, lazyValue) {
   var sentinelUndefined = {};
   var sentinelInProgress = {};
   prototype[fieldName] = sentinelUndefined;
-  var getter = new Function("{ return $isolate." + fieldName + ";}");
   prototype[getterName] = function() {
     var result = $isolate[fieldName];
     try {
@@ -350,8 +357,7 @@
     } finally {
       $isolate[getterName] = getter;
     }
-  };
-}""";
+  };""";
   }
 
   void addDefineClassAndFinishClassFunctionsIfNecessary(CodeBuffer buffer) {
@@ -1336,11 +1342,16 @@
         buffer.add(namer.getLazyInitializerName(element));
         buffer.add("', ");
         buffer.add(code);
+        emitLazyInitializedGetter(element, buffer);
         buffer.add(");\n");
       }
     }
   }
 
+  void emitLazyInitializedGetter(VariableElement element, CodeBuffer buffer) {
+    // Nothing to do, the 'lazy' function will create the getter.
+  }
+
   void emitCompileTimeConstants(CodeBuffer buffer) {
     ConstantHandler handler = compiler.constantHandler;
     List<Constant> constants = handler.getConstantsForEmission();